Living in an active earthquake region, there are few of us who remain unaware of the many faults in the bay area. Some people prefer not to dwell on the inevitable risks, but others choose to learn more about earthquake geology. There are two places in the bay area with interpretative earthquake trails for hikers, both on the San Andreas Fault. Point Reyes National Seashore hosts their Earthquake Trail at the Bear Valley Visitor Center, while the Midpeninsula Regional Open Space District created the San Andreas Fault Trail at the Los Trancos Open Space Preserve. Los Trancos' hiking-only trail features 9 stations and an accompanying brochure, which instruct about sag ponds, benches, and other earthquake phenomena. This is a small preserve, but you can combine the easy earthquake circuit with two other loops at Los Trancos, for hikes from 2 to 3 miles. There's one out-and-back hike via the Page Mill Trail, but as that trail edges along backyards and Page Mill Road, that's not a hike I would recommend.
     From the trailhead, walk to the west edge of the parking lot and look for the start of the San Andreas Fault Trail. The narrow path, open to hikers only, climbs a few feet to a viewpoint, and station 1 of the earthquake trail. From the vista you can see south past Monte Bello Open Space Preserve (dominated by Black Mountain), to Mount Umunhum and Loma Prieta (23 miles away). The San Andreas Fault divides the American and Pacific Plates here, and the seismic activity on the fault zone has altered the surrounding landscape. The sag pond north of the parking lot was created by the 1906 earthquake. Continue to station 2, near a stone bench with great views east to Mount Diablo, and north to downtown San Francisco and Mount Tam. Follow the path downhill through gooseberry and coyote brush, cross a meadow where you may see yellow mariposa lily, paintbrush, California poppy, clarkia, larkspur, owl's clover, and brodiaea blooming in late spring, and then arrive at an unsigned junction at 0.16 mile. Bear left, and a few steps later, at a signed junction, continue straight on the San Andreas Fault Trail.
     Thick foliage lines the path, including young madrone, blue elderberry, toyon, California coffeeberry, creambush, coyote brush, poison oak, coast live oak, canyon live oak, California bay, and ferns. At 0.43 mile, you'll reach station 3, and a signed junction. Double back to the left on the Fault Trail.
     The deeply shaded trail descends gently through California bay, oaks, creambush, wood rose, and hazelnut. Station 4 showcases probably the most famous and photographed feature at Los Trancos, a reproduction of a fenceline that moved 3 feet to the northwest during the 1906 quake. After a few more steps, at 0.46 mile, the trail splits at a signed junction. You can go either direction, but the earthquake tour progresses clockwise. Bear left.
     You may see fairy lanterns nestled close to the ground in spring. In summer, rosehips add a blast of red to the understory. Black oaks mingle with the other trees. The San Andreas Fault Trail continues through to station 9. When you reach the formerly encountered junction, at 1.13 miles, bear left, and return to the previously encountered junction with Franciscan Loop Trail at 1.16 miles. Turn left onto Franciscan Loop Trail.
     The hiking-only trail ducks under a few large California bays and a handful of huge old oaks, then gently descends to a signed junction at 1.18 miles. Page Mill Trail sets out to the right. Continue left on Franciscan Loop Trail.
     Once a meadow has been bisected, Franciscan Loop Trail enters shade and follows along Los Trancos Creek. You may seen columbine, woodland star, baneberry, snowberry, honeysuckle, and bluewitch nightshade languishing beneath oaks and California bay. Hazelnut shrubs are plentiful, and produce nuts in late spring. Staples for squirrels, you have to look hard to find the nuts (in fact, if they're still on a branch in early summer, they probably are not yet ripe). After a short, well-graded descent, you'll cross a creek (more like a swamp), which is jungle-like in the summer, on a volunteer-built causeway. Tangles of blackberry, tall poison hemlock, California coffeberry, snowberry, and elderberry flourish in the damp spot. At 1.44 miles, Franciscan Loop Trail meets a connector to Page Mill Trail at a signed junction. Continue straight on Franciscan Loop Trail.
     Continuing to descend along Los Trancos Creek, the trail is heavily shaded by California bays and a few big-leaf maple. A dramatic rock reef makes an unexpected appearance; the trail passes through the middle of the formation, then meets the connector to Lost Creek Loop Trail at a signed junction at 1.60 miles. (If you'd like to shorten this hike, go left, continuing on Franciscan Loop Trail.) Stay to the right (straight really), and after a few steps, bear right onto Lost Creek Loop Trail.
     This narrow hiking only path cuts through a tangle of underbrush, then drops down to a boardwalk over a wet area. In summer, you may find berries on a currant bush off to the right. Upon reentering the woods, quiet shade prevails. A large shrub of pitcher sage puts forth blossoms in the spring, accompanied by ferns, poison oak, snakeroot, hound's tongue, and giant trillium. At 1.80 miles, Lost Creek Loop Trail meets Page Mill Trail at a signed junction. Turn left.
    The two trails run together, then at 1.90 miles, Page Mill Trail breaks off to the right. Continue straight on Lost Creek Loop Trail.
     Thimbleberries are profligate along the high banks of the creek, as are seep monkeyflower, ferns, and baneberry, which has bright red berries in the summer, but unlike edible thimbleberry, is poisonous. Tanoaks make an appearance, and soon you might notice pine needles scattered across the trail, indicating the presence of Douglas firs. The quiet of the woods may be broken solely by birds and the constant gurgle of water. Lost Creek Loop Trail draws near to Los Trancos Creek, than runs along the banks for a few feet, leaving the creek to begin an ascent. The path contours around a hill, then climbs some more. In the late spring, look for spotted coralroot among downed oak leaves. Some madrone and big-leaf maple provide color along the trail in fall; maples color and then shed their leaves, while madrones drop strips of their bark, and produce large, bright berries later in winter. Lost Creek Loop Trail ends at a previously encountered junction at 2.50 miles; turn right onto Franciscan Loop Trail.
      The trail drops down to cross Los Trancos Creek on a bridge, then travels through a small stand of Douglas fir as it resumes climbing. Overall the grade is easy, although there a few short steep sections. Soon Franciscan Loop Trail makes a level return to the chaparral-bordered grassland. You may glimpse more fairy lanterns in the spring, or clarkia, yarrow, and yellow mariposa lily blossoms that can persist into early summer. At 2.95 miles, Franciscan Loop Trail ends at a previously encountered junction. Continue to the right (the unsigned common path straight ahead ends at the same place), following the sign back "to Page Mill Parking."

Total distance: 3.03 miles
Last hiked: Friday, August 17, 2001


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